


Unnatural

by mabelsguidetolove



Category: Gravity Falls
Genre: F/M, Incest, Older Characters, Purple Prose, Sibling Incest, Smut, Twincest
Language: English
Status: Completed
Published: 2016-02-21
Updated: 2016-02-21
Packaged: 2018-05-22 09:34:37
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 807
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/6074176
Author URL: https://archiveofourown.org/users/mabelsguidetolove/pseuds/mabelsguidetolove
Summary: <blockquote class="userstuff">
              <p>Your standard smut. Not much to say. A reflection on their unconventional relationship.</p>
            </blockquote>





	Unnatural

_You know, it’s unnatural for siblings to get along as well as you do._

Those words, though spoken several summers ago, flashed through Dipper’s head like a distant whisper as his eyes met with his twin’s, a desperate gaze from both ends.

 _You don’t know the half of it, Stan,_ he thought to himself; after all these years, he and Mabel were still sharing a room together in the attic for the summer. But it wasn’t as innocent as it had been before, not nearly. Currently, she was lying down in front of him, wearing nothing but a pair of panties with the face of a panda bear on the front.

And it was driving him mad.

“We’re alone, you know,” a familiar voice faltered as doe eyes looked up at him thirstily, like a silent dare. Something about her grin almost looked catlike. “You can touch me of you want.”

It wasn’t the first time they’d had trysts like this, and it certainly wouldn’t be the last time. But they had never made it this far before, and Dipper always needed a warm-up period, if you will, to curb the anxiety he felt whenever they were this close.

“Of course,” he chuckled awkwardly. “I just always remember the walls of the shack being thinner than they are, you know?”

With a couple of fingers, he slowly grazed the outline of her panties, eliciting a small moan.

”Wow, you’re… Really wet right now, aren’t you?”

“Mm-hmm,” she nodded, raising a hand to her face to hide an all-too-obviously devilish smile. “I’ve kiiiinda been looking forward to this all day.”

 _Okay, easy_. Dipper was surprised; he thought he’d need a lot more foreplay to be able to do this. He’d even looked up some tips on the Internet because he wanted to do it right. But more than that, he also really wanted to be inside her.

Clumsily, he grabbed the waistband of his boxers and pulled them down, eventually taking them all the way off. He caught Mabel taking one or two (faux-)bashful glances at him, but he didn’t say a thing. The anticipation grew greater for them as he precariously lined up his own hips with hers, and Dipper felt something in him tense up as he finally took the plunge, her slick walls tightening gently around his cock. It felt so good. So, so fucking good. And Mabel’s moaning only intensified the sensation as he began to thrust, her hips rolling back into him, validating that yes, this sick fantasy of his was really happening. And they were both enjoying every second of sin, indulging in every tiny moment.

“Mabes,” Dipper murmured laviciously between sloppy, heavy kisses that wavered up and down her décolletage, prompting her to let out slight whimpers every so often as he pumped in and out, in and out of her. “You’re so goddamn beautiful…”

“Ah, _noooo_ , I love you,” she whined, her short fingernails digging into his back. Her eyes appeared dewy as her soft curls bounced subtly in sync with her pert breasts, pleasure blooming inside her, getting stronger with every pulse, every stroke. Her back began to arch against the bed as she began to reach her threshold.

Dipper’s eyes wrenched close, sweat forming on his knit brow. “I’m so close,” he groaned into his sister’s ear, sending shivers down her spine.

"Finish,” she commanded desperately. “Finish inside me…”

That final plea alone was enough to make him do just that. He exploded inside of her, his mind going blank as he pulled her into a final kiss. And from the stinging sensations on his back, her nails gripping onto him tighter than ever, he knew that she’d reached her limit at just around the same time. This release, this glimpse at utter paradise, must have nearly sent Dipper’s mind into sleep mode, because the next thing he knew, he was pathetically flopped onto the bed right beside the girl he loved, practically sharing the same heartbeat as her as they wearily entwined their fingers together, looking at each other as if they both saw the entire universe in the other’s face.

“Wowie,” Mabel giggled suddenly, pressing her forehead to Dipper’s as her dark eyes formed crescents. “We… We really did that!”

“Yeah,” he replied dreamily. “We did, didn’t we?”

Grunkle Stan was right; it definitely was unnatural for the two of them to be this close. And he definitely didn’t know the extent of it. Both twins knew that everything about this was wrong, so deliciously wrong, and trouble would always be on the horizon if they were to continue to be so reckless with one another. What they were doing was, on all accounts, positively insane.

But when it came down to it, neither Dipper or Mabel would have ever wanted it any other way.


End file.
